solve absolute value inequalities © 2011 the enlightened elephant
TRANSCRIPT
First, let’s think about what absolute value inequalities are
really asking us to find!
© 2011 The Enlightened Elephant
4x All the numbers whose distance from zero is greater than 4.
-4 4
4x 4xor
***Notice that you need to have two inequalities to represent the distances that are greater than 4 from zero.
What does really mean? 4x
© 2011 The Enlightened Elephant
4x All the numbers whose distance from zero is less than 4.
4x 4x-4 4
and
***Notice that you need to have two inequalities to represent the distances that are less than 4 from zero.
However, since these inequalities must happen at the same time, it should be written as
44 x
What does really mean? 4x
© 2011 The Enlightened Elephant
Solve and graph
Step 1: Isolate the absolute value.
842 x
44 x
44 x 44 x
8x 0x
0 8
© 2011 The Enlightened Elephant
Step 2: Set up two inequalities.
Step 3: Solve the
inequalities.
Step 4: Graph the solutions.
You Try!
Step 1: Solve and graph.
Step 2: Step 3:
Step 4:
Step 5:
11124 x
32 x
32 x 32 x
1x 5x
-5 1
Final answer: -5<x<1© 2011 The Enlightened Elephant
You Try!
Solve and graph.
93 x
93 x 93 x
12x6x
-12 6
Final answer: 12x6x or
Set up two inequalities!
© 2011 The Enlightened Elephant
You Try! Solve and graph.
21123 x
712 x 712 x
3x4x
-3 4
Final answer: 3x4x or
Isolate the absolute value
first!
712 x
© 2011 The Enlightened Elephant
You Try! Solve and graph.
15363 x
1263 x 1263 x
2x6x
Final answer: 62 x
Isolate the absolute value
first!
1263 x
-2 6
© 2011 The Enlightened Elephant
You Try! Solve and graph.
238123 x
512 x 512 x
3x2x
Final answer: 23 x
Isolate the absolute value
first!
512 x
-3 2
© 2011 The Enlightened Elephant
You Try! Solve and graph.
1282 x
Final answer: NO SOLUTION!
Isolate the absolute value
first!
Absolute values are distances, which cannot be negative.
You can choose any value for x and the left side of the inequality will
always be positive. However, positive numbers are
NEVER less than negative numbers.© 2011 The Enlightened Elephant
You Try! Solve and graph.
10126 x
Final answer: ALL REAL NUMBERS!
Isolate the absolute value
first!
Absolute values are distances, which cannot be negative.
You can choose any value for x and the left side of the inequality will
always be positive. Positive numbers are ALWAYS
greater than negative numbers.
© 2011 The Enlightened Elephant